Electric-circuit tracer



Aug. 14, 1928.

H. R. BARTLETT ELECTRIC CIRCUIT TRACER Filed Dec. lO, 1926 www@ m m m lSenn, c e

iff-2 @Hoang Patented Aug. 14, 192,8. y

UNITED `STATES HENRY a vBARTLETT, "or WEST HAaTroaD, CONNECTICUT.

ELECTRIC-CIRCUIT '.IRACER,`

' Application led December 10,1926. Serial No. 153,828.

This invention relates to means which are designed for the use of wireinspectors, contractors, installers and others interested in tracingconcealed electrical circuits, that is, in ascertaining what lamps,heaters, motors cr otherl electrical apparatus or implements are on aparticular circuit.

The object of the invention is to provide an inexpensive device for thispurpose which is easily transported and simple to use and that will givea visual indication of what apparatusor implements are in the circuit towhich it is applied without interrupting or interfering with the supplyof current to the load on that circuit.

This'object is attained by arranging in a portable box, a transformer'and a magnetic circuit control, with suitable resi-stance and ampleprotecting means, and means for introducing the transformer in 'serieswith a line and the control across the line or other source of current,whereby when the proper connections are made with a circuit there Y willbe a variation of the voltage ofthe ciri in the action ot' theapparatusor Vimplements in that circuit, but not in any other circuitconnected with thesame mains. y

In the accompanying drawings Fig. 1 shows a vertical section of the boxprovided withA one arrangement of means for accomplishing the object `ofthis invention. 1 Fig. 2 is a diagram of the elements and theirconnections in 'the relative positions occupied before being connectedwith the circuit to be traced. Fig. -3 isa diagram `showing theapparatus connected Withacircuit, the armature of the magnetoscillating'between the l contacts of the control and one winding o thetransformer.

The case orbox 1 may be made of wood or any other suitable material.`The top 2'otI `the `box isdesirably made of'an insulating.

compound with perforations 3 for allowing ventilation, while the frontof the boX'preerably is an insulating panel 4with the activeelementsfastened thereon. Y

The transformer is a common type comprising a core 5 and windings 6. For the urposeof illustration the output winding l is indicated by 7 andthe inputwinding indicated by'8. The output Winding 7 is designed to beconnected in series with the load on the circuit-to be traced and it.has sufficient capacity to carry the full current ,flowing in thecircuit, that is, the impedance cuit which Will cause a `distinguishableetl'ect of this winding is such that no appreciable loss o f poweroccurs by introducing it into the circuit. In the particular embodimentof the invention illustrated one terminal ot the .output winding isconnected by a wire 9 with a binding post 1() on the front panel, a'tuse11 of common type being insertedV in this connection for the purpose ofprotection. lhe ,other terminal of the output winding 1s connected witha post 12 leading from Whlch'to the binding post 13 on the front panel1s a wire 14. The opposite sides of a common plug 15 are removablyatt-ached to these posts. In approved light-and power circuits there arecutouts, these being represented in the diagrams by 16. When the traceris to be used one of the cutouts, whichv may be a use plug, is removedand the plug connected with the output winding of the transfer isinserted in its lace, thus putting this winding in series wit the loadonthat circuit. The tracer plug could, of course, be inserted in a lampsocket if there was no fuse socket.

The inputtranst'ormer winding 8 which is indicated as having greaterresistance than r the output winding, is adapted Vto be con `nected'with a source of electrical energy,

preferably across the, circuit to be traced, and theenergy of thisVwinding is controlled by means of aivibratory Acircuit make and break.One terminal or the input Winding is connected with the post 12 that, asabove described, i'selectrically connected with the plugl. The otherterminal of the input winding is connected bywire 17 ywith av con-Aducting plate 18 `fastened to the front panel. This plate is inelectrical engagement with a screw 19 that carries a sleeve 20 holding acarbon contact 21. A spring 22 is arrangedin the sleeve to cushion thekcontact. Connected with the screw is a linger nut 23, by turning whichthe exact position of the end of the carboncontactimay Vbe determined.

,The make 'andbreak illustrated includes an electromagnet shown ashaving two connectedcoils'24 with cores 25 and armature 26. One terminalof the magnet winding is connected by Wire 27 with one end of aresistance 28 of known type, that is fastened to the topv of the boX.-The other end Vof the f resistance is connectedby wire 29 with the post12 that, as above stated, is connected with one side of the attachmentplug 15. The other terminal of the magnet winding is connected by a Wire30 to a conductingplate` 3l attached tothe front pan`el.- 'lhisgplatc isin an electrical-engagement with a screw 32 that carries a sleeve 33which holds a' carbon contact 34. A spring 35 vis arranged" in thesleeve to cushion this contact,y Connected with this screw is a fingernut SGby turningl which the end `of this VKContact may be justed.

Arranged between these yrelatively stationarycontacts is ya `movablecarbon contact 37 that is carried bythe long arm; of, a )r1duct l i.inglever 38 which,istpiyotedtoplate 39 by screw 40,; This plate isAconnected by a, Wire 41 with apostw42towvhich aclipunay `be connected..A fuse tlanay `be inscrtedin this line, if desired. Theother arm of then conta-,ctr carryingglever is Ajlonsely. lerlg/ui-ged g mally remain`.in*engagement with theiixed contact 34:.. There is aslnall lost motionencgagemel,1t.lzietween the'. block 44 andthe end ofthe short arm of thelever so that thjeeontact will notbe disengaged the; instant that thearmature moves but WillQholdtfor a f short interveh .A wcighua): is eattached to the end. of the long. streef l.the movable .contact lever,kand .the :block i `filet, also ,hasscme .Weight tthe .1`1icrtiaofvwhich is.. utlizedtto .reduce the rapiditv ot esclletionof-the movable`co1'1ta,et,. eny insure. arelatiyelyV slow rcciprocation of, theymovable QOHHLC-.When

l To ascertain Ternat.I avpparatusfol. linents are 1n a particular`,circuit a cutouton l yfuse isLremoved fromthat circuitand,.the

. plug ofthe, tracer. is substituted.JVA ,Y This V,puts the output, orlow impedance windingl ofrthe transformer in series with; the load-lon`.that circuit.; The clfipisthenengagcd witha live l part, of, theopposite leg `oiA the, circuit. Lto. be

traced., This connectsthc magnetffwinding f f andinput winding ofthetransformeren-1h58 fthe ,circuit,tolbe\traced. k As this isdone the 5magnet is,energiiedandth'iilwllg,thefarmature causes ai break; l1n i the`nutgnetic circuit .electromagnetic means. adapted to, open and lclosethe circuit A. throught said second menand completes the circuit acrossthe line f through the input Wuding-goiithe transformer.This-rallowsgeurrent to iioy through the' input. Winding of thetransformer'which f.

of course affects the'voltage inA theoutputi. winding..Asthemagnetmcircuit breairsthe spring` withdraws .the armature anduremakes n `the `magnet circuit.y 'I hisfaction repeats as A longfas theclip` held in' contact ivith the '1" line.` Owing'tofthelostmotionbetween the armature Vand the.' 'movable c'oi'itact`:'arrying"`h lever that lever do'esfnt 'move' to disengage the contactsinstantly the armature moves, while the inertia of the' Weights adds tothls slowing 'of movement of the movable contact, 'andfyet insures agoed `contact when made. y *c `Adjustment for the wear of the contactsisrcadily made `by means of the finger nuts, andthe blows the movablecontact against the stationary contacts are cushioned bythe springs backof the stationary comme.. t..

The ychange of 'energy in the input windingof thetransformer due to theopening and closingirofythe circuit in which it is locatedl causes avariatihnin the current of the output Winding and this in turn causes adistinguishable"variation in the voltage o the circuit being `testedwhich, for instance iftheload is lighted lamps .will caus'call of thelamps in that circuit to ,flickerpr low lwith 'a different degree of.brightness rom normal and thus showf what is connected in the circuitto which the tracer` is connected. KThe invention claimed is i,

- ,1.7, Aportahle n. electrical circuit tracer comprising a transformerhaving out ut .and input windingsn1eans for detachalbl yconnecting theoutput Winding in series wit the` loadon the circuit rto betraced.,means for detachablyconnccting the input winding across the cia'cuittoIhe traced, .and electromagneticlmeans for makingI and break- .ingConnection, tofsaid input 'winding'.

wZIAMQOEablQ.; electrical circuit tracer comprising aA transformerhaving out nut and inputwindingswmeans for detacha .1y

Connecting the;4 Output Winding ill Series ,means for detachahlyconnecting the input :Winding across. the circuitto be traced, and

electromagnetic; means with means for connectmg said ElectromagneticLmeans across to Said. electromagnetic meansr 3. Afpolgtable electricalcircuiti,

comprising a. transformer having a winding withr circuit connectionsadaptedtointro tioncd transformer winding, andthereby vary ,the voltagein the circuit of the rst .mentioned winding.`

duce said minding inscrieswith the load of ,.1 the circuit, to betraced,andawinding with ppiltcuit..connectionsadapted to connect lscidWinding-acrossftlle Circuit to. be traced,xand

4. A .portablen electrical circuit ftrac'ien Windingof low impedancewith circuit confnections adapted to introduce said `windingVcomprisinga transformer having an output 'connect sa-i'd"ivindingacross the circuitto 130 be traced, and electromagnetic meansadapted to open and close the circuit through the transformer inputwinding and thereby vary the voltage in the circuit of the outputwinding.

5. A portable electrical circuit tracer comprising a transformer havingan output Winding with circuit connections adapted to introduce saidWinding in Vseries with the loadof the circuit to be traced and an in utWinding with circuitconnections adapte to introduce said Winding acrossthe circuit to be traced, an electromagnet with circuit connectionsadapted to connect the magnet windings across the circuit to be traced,and

Vmeans subject to the magnet for alternate ly opening the magnet circuitand closing the input circuit.

G. A portable electrical circuit tracer comprising a transformer havingan output Winding With circuit connections adapted to introduce saidWinding in series with the load of the circuit to be traced and an inputwinding with circuit connections adapted to connect said winding acrossthe circuit to be traced, an electromagnet With circuit connect-ionsadapted to connect the magnet windings across the circuit to be traced,vand an armature sub'ect to the magnet, a Contact actuated by saiarmature and adapted to alternately open and close the circuits throughsaid magnet and input Winding, there being a lost motion connectionbetween the armature and said contact.

7. A portable electrical circuit tracer comprisingV a circuit containinga transformer output Winding, a fuse and means adapted to connectsaidcircuit in series With the load of the circuit to be traced, acircuit containing a transformer input Windingv and means adapted toconnect said circuit across the circuit to be traced, a circuit containing an electromagnet and means adapted to connect said circuitacross the circuit Ato be traced, and means adaptedto alternately openand close the circuits containing said transformer input Winding andsald magnet. 1

HENRY R. BARTLETT.

